/*
 * Copyright (C) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.io;

import java.io.File;
import java.io.FilenameFilter;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

import com.google.common.base.Preconditions;

/**
 * File name filter that only accepts files matching a regular expression.
 * 
 * @author Apple Chow
 * @since 2009.09.15 <b>tentative</b>
 */
public final class PatternFilenameFilter implements FilenameFilter {

    private final Pattern pattern;

    /**
     * Constructs a pattern file name filter object.
     * 
     * @param patternStr
     *            the pattern string on which to filter file names
     * 
     * @throws PatternSyntaxException
     *             if pattern compilation fails (runtime)
     */
    public PatternFilenameFilter(String patternStr) {
        this(Pattern.compile(patternStr));
    }

    /**
     * Constructs a pattern file name filter object.
     * 
     * @param pattern
     *            the pattern on which to filter file names
     */
    public PatternFilenameFilter(Pattern pattern) {
        this.pattern = Preconditions.checkNotNull(pattern);
    }

    /* @Override */public boolean accept(File dir, String fileName) {
        return pattern.matcher(fileName).matches();
    }
}
